Ignition timing device



April 1943- c. COLVIN 2,317,885

IGNITION TIMING DEVICE Filed Aoril 15, 1942 [ii/70rd [6/1/02 INVENT OR.

Patented Apr. 27, 1943 IGNITION TIMING DEVICE Cliflord Colvin, Detroit, Mich, assignor to George M. Holley and Earl Holley Application April 15, 1942, Serial No. 439,065

1 Claim.

is lost, because the part throttle spark advance is retarded although the knock occurs chiefiy at wide open throttle and at throttle almost wide open, and especially when the throttle is opened quickly, that is, faster than the engine picks up.

The figure shows diagrammatically the essential elements of my invention.

In the drawing, I is a bridge supporting the fuel nomle in the air entrance; H is a venturi in which the nozzle discharges; I2 is a throttle located in the mixture outlet l3. A passage l4 communicates with the mixture outlet l3, through a passage [5, the moment the throttle valve I2 is opened a few degrees. The restriction IS in this passage determines the effect of the suction in the mixture outlet on the ignition advance for road load. A restriction H in the passage ll communicates with the venturi ll through the opening l8, which is at least equal in area to the opening IT. The restrictions I8 and II are so adjusted that when the throttle is partly opened the suction created in the mixture outlet I3 is modified by the lackoi suction in the throat of the venturi H. The resultant of the suction is sumcient to advance the spark sufficiently to give the desired mileage. When the throttle is wide open the suction in the venturi II is modified by the lack of suction at the point I and again the suction is sufllcient to advance the spark the desired amount at wide open throttle.

The suction thus modified is transmitted through the pipe 2| to the chamber 22, one wall of which is formed of a diaphragm 23 connected by a link 24 with an arm 25 of the circuit break-v the low tension side of which is connected with the battery ll and the high tension side is connected to the distributor 88.

It will be noted that when the throttle I2 is closed, the opening 15 is no longer subjected to engine suction so that the engine idles with a retarded spark.

When a low grade fuel is used, a needle valve 19 is opened admitting air from the opening 20 which communicates with the air entrance and so minimizes the effect of the suction in the venturi II. The effect of opening the needle valve I9 on the part throttle advance is practically nil because the restriction I1 is equal to the restriction l8, so that the reduction in the suction at part throttle is the same as if the needle Ill is closed.

Hence at wide open throttle, the spark advance is not as great as it otherwise would be but the road load spark advance is practically unchanged.

The result is that a low grade fuel can be used without sacrificing very much mileage because tank mileage is determined mostly by part throttle performance, or roadload mileage as it is termed. At wide open throttle there will be a loss but high mileage is impossible at wide open throttle.

What I claim is:

In an internal combustion engine a carburetor having an air entrance, a venturi therein, a mixture outlet, a throttle valve therein, an ignition system for said engine including a low tension circuit breaker, a chamber associated therewith having a movable wall, said movable wall being adapted to advance and retard said low tension circuit breaker in response to an increase or a decrease of suction in said chamber, a passage connecting the chamber with the mixture outlet at a point adapted to be subjected to the mixture outlet suction whenever the throttle is moved from its closed position, a restriction in said passage, a second passage connecting the throat of the venturi with the first passage at a a point between said restriction and said chamher, a restriction in said second passage, and an adjustable opening admitting the air at substantially atmospheric pressure into said second passage at a point between the restriction therein and the throat of the venturi.

CLIFFORD COL-VIN. 

